In the post-genomic era, an estimated 25,000 to 30,000 genes are thought to encode the complex human proteome. However, the challenge remains to understand the multitude of RNAs and proteins derived from this deceptively small number of genes and to understand their interactions and function in health and in disease. Alterations in RNA splicing and protein processing result in the much higher complexity than is evident in the human transcriptome and in turn the proteome. Nowhere in the human body is this leap in complexity from genome to proteome more evident than in the brain. There is therefore tremendous opportunity for discovering new proteins and protein function in the brain with commercial potential for novel therapeutic and diagnostic products. We propose here to identify novel neuroendocrine brain proteins of therapeutic significance. Our approach will be to mine the hypothalamic secretome, the portion of the proteome that encodes secreted and membrane bound proteins. This class of proteins, which is one of the most abundant sources of drug targets and protein based therapeutics, includes peptide hormones, growth factors and cytokines which play a critical role in maintaining health through cell-cell communication. We will use a novel phage particle display strategy designed to identify active ligands from within larger protein precursors to identify novel ligands and their target cells. In our phase one study, we will perform proof of concept experiments on the hypothalamus as it is an important source of regulatory hormones that affect multiple organ systems in the body. Our first aim will be to identify secreted and membrane bound proteins from a human hypothalamic cDNA library using a signal sequence trap. In our second aim we will select active ligands from the secretome using phage display. A fragmented secretome cDNA library will be displayed on phage particles from which we will select the active ligands using functional screens on target cell lines. In phase II, we will characterize the expression pattern to elucidate the functional significance of our lead ligands and we will mine additional ligands from the hypothalamus. We will develop near term revenue from commercialization of ligand based research reagents, such as growth factors, antibodies, and ELISA kits based on the discovered ligands. Our long term goal will be to select the most promising lead ligands for therapeutic and diagnostic development and phase III commercialization. PUBLIC HEALTH RELEVANCE: In the post-genomic era the challenge is to fully understand the protein products of the human genome and how these function in health and disease. One therapeutically important class of proteins is the so called "secretome", those proteins that are secreted from cells and are important for cell to cell communication. We propose to identify new and novel secreted proteins made in the hypothalamus, a complex brain region that links the body's perception of its environment with its regulation of body functions such as temperature, blood pressure, appetite, digestion, and sleep. It regulates the master gland of the body, the pituitary, and effects emotions and behavior. We will identify new proteins and active protein fragments from the hypothalamic secretome using novel protein display and selection technology. We will develop and commercialize antibodies and detection kits for the novel proteins and assess their diagnostic and therapeutic potential.